The invention relates to an adjustable stop apparatus for limiting movement of an element of a metering valve for setting a flow limit condition of the valve.
An adjustable stop apparatus for a metering valve is known comprising a stop S, a housing H, and a rotary adjuster device D connected to the stop S. Such a device is shown in FIG. 1 fitted to a metering valve. The position of the stop S is normally adjusted by means of the rotary adjuster device D in a factory environment during assembly of the valve, and die rotary adjuster device D is then locked in position with a lock nut N. The valve user would not be expected to carry out further adjustments to the position of the stop S of the known device. Therefore, a tamper resistant cover C is generally fitted to the stop apparatus covering the lock nut N.
In accordance with the invention, an adjustable stop apparatus is provided for limiting movement of an element of a metering valve for setting a flow limit condition of the valve, the apparatus comprising a stop, a housing, a rotary adjuster device connected to the stop for adjustably positioning the stop relative to the housing, and a guide device operable to guide the adjuster device relative to the housing into a plurality of alternative preset positions determined by the guide device.
This provides the facility for a user to switch between pre-set positions without necessitating any variable adjustments or precision setting techniques. In his manner, a single stop apparatus can be kept by a user and adjusted by the user to provide a variety of different flow limit conditions according to requirement. This obviates the need to store several stop apparatuses for different requirements.
Preferably, the guide device releasably secures the adjuster device relative to the housing in said pre-set positions.
The guide device conveniently comprises a sleeve having a plurality of slots, each slot corresponding to a respective one of set pre-set positions and being selectively alignable with a projection fixed relative to the housing.
Rotary movement of the adjuster may be permitted by the guide device only within a selected arc between said pre-set positions. This helps prevent confusion when re-positioning the stop, and prevents the adjuster device being turned beyond said pre-set positions resulting in an undesirable stop position.
Conveniently, a peripheral portion of the sleeve is extended axially beyond the rest of the sleeve to provide a lug which limits the extent of rotary movement of the guide device in its released condition.
Preferably, the apparatus further comprises resilient biasing means biasing the guide device in a direction tending to secure the adjuster device relative to the housing.
The biasing means may comprise a spring disposed within the guide device and acting between an abutment fixed relative to the adjuster device and a laterally inwardly extending portion of the guide device.
Conveniently, the guide device has an external groove or projection for engagement by a tool, for placing the guide device in a released condition in which the adjuster device is movable relative to the housing, and the housing has a correspondingly positioned access aperture for accessing the groove or projection with the tool.
Markings may be provided on the guide device for indicating a present position of the guide device, the markings being viewable through the access aperture
The markings may include a triangle arranged to indicate, in use, in which direction the guide device should be moved to obtain a greater or lesser flow limit condition of the metering valve.
The guide device may have a flat sided portion for engagement by a rotary tool, the arrangement being such that the flat sided portion projects from the housing for access by the rotary tool only when the guide device is in the released condition.